Scroll wheels have been provided on computer mice and used by computer operators to move an image relative to a display screen of a host computer. A scroll wheel assembly includes a rotatable scroll wheel and a sensor that are typically included in a housing for a peripheral computer device such as a mouse. Typically, a portion of the scroll wheel protrudes upwardly out of an opening in its housing and is rotated in order to vertically scroll the image along the screen.
Scrolling, as used herein, describes the movement of an image relative to a display screen in a particular direction as such term is commonly used in the art. For example, the term “scroll down” as used herein relates to moving the viewable contents of a file (such as a text document or image) relative to display screen by an amount to produce an effect of moving down in the document or image. Similarly, the terms scroll up, scroll left and scroll right relate to moving the viewable contents of a file relative to a screen by an amount to produce an effect of moving in the document or image up, left, and right, respectively. The term scrolling as used herein also includes panning, which is the automatic scrolling of an image.
In operation, a conventional scroll wheel is normally rotated about a first, transversely extending axis secured within a housing in order to scroll the image up and down (vertically) relative to the display screen. As the scroll wheel is rotated, an encoder senses the rotation of an encoder wheel and delivers a corresponding signal to a host computer which in turn can be used to move an image as is known in the art. This can occur without the user moving the position of the mouse and/or the cursor. However, many types of documents, such as spreadsheets, are usually wider than the width of the display screen and the user may want to scroll horizontally across the screen to see the entire file. When the user needs to move the image horizontally across the display screen, the user must typically stop what he or she is doing and perform a number of tedious and potentially frustrating steps. These include locating a graphical user interface in the form of a horizontal scroll bar usually located near the bottom of the display, positioning the cursor on the scroll bar, and then rotating the wheel. Locating the scroll bar can be very difficult for people with bad eyesight, small display screens and/or poor hand-eye coordination. As a result, the user will waste time and delay the completion of his project while fumbling to find the bottom horizontal scroll bar. These delays can cause the user great frustration and unnecessary stress that is magnified when he or she is operating under a deadline.
If the user does not accurately position the cursor over the horizontal scroll bar, the image will not scroll horizontally with respect to the display screen as he or she rotates the wheel. Instead, the image will move vertically relative to the display screen and erroneously change the displayed image. This error will force the user to take additional steps to reposition the desired image on the display screen. These steps include the user confirming that the cursor is not positioned on the horizontal scroll bar and rotating the scroll wheel in the opposite direction to return the image to its previous position. Unfortunately, repositioning an image can lead to errors if the image is being amended. For example, the user may not return the image to its previous position. As a result, he may amend the wrong section of the image. Even if the proper image or portion of an image is returned to the display screen, the user must still attempt to locate the bottom, horizontal scroll bar a second time in order to finally move the image in a horizontal direction.
An existing mouse design includes a first rotatable wheel for scrolling an image up and down, and a second, separate rotatable wheel for scrolling an image left and right. The rotatable wheels are oriented so they extend and rotate in planes that are perpendicular to each other. The two scroll wheels are independently operable. However, this arrangement has drawbacks as the two wheels take up valuable upper surface area on the mouse which could be used for supporting the hand of the user or for additional input keys. Further, the two wheels have been made to be a small size to accommodate both wheels on the upper surface of the mouse. The smaller sized scroll wheels make the scrolling more difficult to control. Additionally, the location of the horizontal scroll wheel is inconvenient for effective control.